Safety envelope



Jan. 13. 1925.

K. RITTER SAFETY ENVELOPE Filed Sept. l 3 1923 INVENTOR 360ml m TTORNVEIY Patented Jan. 13, 1925.

NIT-ED STTES ii I SAFETY ENVELOPE.

Application filed September 13, 1923. Serial No. 662,375.

To all whom it may concern:

Be it known that I, KARL BITTER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Safety Envelopes, of which the following is a specification.

This invention relates generally to envelopes, and it has for an object the provision of a novel form of safety envelope designed to increase the difficulty of clandestine opening of the envelope, after the latter is sealed, to examine the contents thereof.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawing, and to the appended claims in which the various novel features of the invention are more particularly set forth.

Fig. l of the drawing is a face view of the blank from which my improved envelope is made.

Fig. 2 is a perspective View of the com pleted envelope with the flap open.

Fig. 3 is a horizontal sectional view of the envelope, this view being taken on the line 3-3 of Fig. 1.

Fig. 4 is a transverse vertical sectional view showing the envelope as sealed, this view being taken on the line M of Fig. 3.

In constructing my improve-d envelope I provide a blank consisting of the main panels 10 and 11 which form the front and rear walls of the envelope, the panel 10 having the usual flap extension 12 formed there- )11 at the free edge thereof. At its side edges this panel has formed thereon the Wings 14 which are of roughly triangular shape and which are adapted to overlap when folded down upon the back of the envelope, and are provided with hooked elements 15 on their overlapped ends which engage or interlock with one another. Formed on the free edges of the panel element 11 are the narrow flaps 17 which are adapted to be glued to the inner face of the element 10. The dotted lines 18 in Fig. 1 indicate the places at which the blank is folded in form ing the envelope. A suitable glue coating 20 is placed on the blank and extends comgether, these wings being glued pletely around the margin thereof, the portion covering the flaps 17 being on the opposite face of the blank from that on the flap 12.

In formin the envelope the small flaps 17 are first folded and then the two main panels 10, 11 are folded upon one another, the flaps 17 at the ends being then glued to the panel 10. The wings let are then folded upon the panel 11 and their hooked ends 15 are overlapped and interlocked todown upon the back of the panel 11. The envelope is then ready for insertion of the letter or other article to be contained therein, after which the narrow flap 17 is glued down upon the inner face of the front panel and the main closure flap 12 is glued down upon the back of the envelope.

Instead of making the hooked members 15 integral with the wings I may make the said hooked members of sheets of gelatine or other material which melts or disintegrates under a relatively low degree of heat, these members being glued or otherwise fastened to the wings. In this construction the main flap is formed with an integral tab or extension 12 which is inserted under the said hooked members, the wings 14 not being glued in place until after the envelope is closed. In the event that an attempt is made to open the envelope by steaming this fact will be made apparent by the injury to the members 15.

Having thus described my invention what I claim as new and desire to protect by Letters Patent of the United States is as follows 1. An envelope comprising main front and back members, side wings upon the front member adapted. to engage over the back member, and narrow flaps upon the back member adapted to be glued to the inner face of the front member, and hooked elements upon said side wings adapted to be interlocked together, said hooked elements being in the form of separate members having a low melting point.

2. An envelope comprising main front andback members, side wings upon the front member adapted to engage over the back member, and narrow flaps upon the back member adapted to be glued to the inner face of the front member, and hooked elements upon said side Wings adapted to 5 be interlocked together, said hooked elements being in the form of separate members having a low melting point, and a flap on the front member having an integral tab extension adapted to be inserted under said hooked elements. 10

In testimony whereof I have affixed my signature.

KARL BITTER. 

